Java示例集合大小

import java.util.*;



public class CollectionTest {

   public static void main(String [] args) {   

      System.out.println( "Collection Example!\n" );

      int size;

      HashSet <String>collection = new HashSet <String>();

      String str1 = "Yellow", str2 = "White", str3 = "Green", str4 = "Blue";  

      Iterator iterator;

      collection.add(str1);    

      collection.add(str2);   

      collection.add(str3);   

      collection.add(str4);

      System.out.print("Collection data: ");  

      iterator = collection.iterator();     



      while (iterator.hasNext()){

         System.out.print(iterator.next() + " ");  

      }

      System.out.println();

      size = collection.size();



      if (collection.isEmpty()){

         System.out.println("Collection is empty");

      } else {

         System.out.println( "Collection size: " + size);

      }

      System.out.println();

   }

}